package com.zang.util;

import org.apache.logging.log4j.util.Strings;

import java.io.UnsupportedEncodingException;

/**
 * 字符编码转换工具类
 * unicode转换工具类
 * @author gs
 * @date 2022/6/10 5:49 PM
 */
public class CodeUtil {

    /**
     * unicode转默认字符串，分隔符：`;`
     * @param uCode  示例： #x5230;&#x671f;&#x65f6;&#x95f4;
     * @return 示例： 到期时间
     */
    public static String uniCodeToStr(String uCode) {
        if (Strings.isBlank(uCode)) return uCode;
        StringBuilder sb = new StringBuilder();
        String[] hex = uCode.replace("&#x", "").split(";");
        for (String s : hex) {
            sb.append((char) Integer.parseInt(s, 16));
        }
        return sb.toString();
    }

    /**
     * unicode转utf-8字符串，无分隔符
     *
     * @param theString 示例： "dispName":"&#x5230;&#x671f;&#x65f6;&#x95f4;"
     * @return 示例： "dispName":"到;期;时;间;"
     */
    public static String unicodeToUtf8(String theString) {
        if (Strings.isBlank(theString)) return theString;
        theString = theString.replaceAll("&#x", "\\\\u");
        char aChar;
        int len = theString.length();
        StringBuffer outBuffer = new StringBuffer(len);
        for (int x = 0; x < len; ) {
            aChar = theString.charAt(x++);
            if (aChar == '\\') {
                aChar = theString.charAt(x++);
                if (aChar == 'u') {
                    // Read the xxxx
                    int value = 0;
                    for (int i = 0; i < 4; i++) {
                        aChar = theString.charAt(x++);
                        switch (aChar) {
                            case '0':
                            case '1':
                            case '2':
                            case '3':
                            case '4':
                            case '5':
                            case '6':
                            case '7':
                            case '8':
                            case '9':
                                value = (value << 4) + aChar - '0';
                                break;
                            case 'a':
                            case 'b':
                            case 'c':
                            case 'd':
                            case 'e':
                            case 'f':
                                value = (value << 4) + 10 + aChar - 'a';
                                break;
                            case 'A':
                            case 'B':
                            case 'C':
                            case 'D':
                            case 'E':
                            case 'F':
                                value = (value << 4) + 10 + aChar - 'A';
                                break;
                            default:
                                throw new IllegalArgumentException(
                                        "Malformed   \\uxxxx   encoding.");
                        }
                    }
                    outBuffer.append((char) value);
                } else {
                    if (aChar == 't')
                        aChar = '\t';
                    else if (aChar == 'r')
                        aChar = '\r';
                    else if (aChar == 'n')
                        aChar = '\n';
                    else if (aChar == 'f')
                        aChar = '\f';
                    outBuffer.append(aChar);
                }
            } else
                outBuffer.append(aChar);
        }
        return outBuffer.toString();
    }

    /**
     * 转换字符串的编码
     */
    public static class ChangeCharset {
        /**
         * 7位ASCII字符，也叫作ISO646-US、Unicode字符集的基本拉丁块
         */
        public static final String US_ASCII = "US-ASCII";

        /**
         * ISO 拉丁字母表 No.1，也叫作 ISO-LATIN-1
         */
        public static final String ISO_8859_1 = "ISO-8859-1";

        /**
         * 8 位 UCS 转换格式
         */
        public static final String UTF_8 = "UTF-8";

        /**
         * 16 位 UCS 转换格式，Big Endian（最低地址存放高位字节）字节顺序
         */
        public static final String UTF_16BE = "UTF-16BE";

        /**
         * 16 位 UCS 转换格式，Little-endian（最高地址存放低位字节）字节顺序
         */
        public static final String UTF_16LE = "UTF-16LE";

        /**
         * 16 位 UCS 转换格式，字节顺序由可选的字节顺序标记来标识
         */
        public static final String UTF_16 = "UTF-16";

        /**
         * 中文超大字符集
         */
        public static final String GBK = "GBK";

        /**
         * 将字符编码转换成US-ASCII码
         */
        public String toASCII(String str) throws UnsupportedEncodingException {
            return this.changeCharset(str, US_ASCII);
        }

        /**
         * 将字符编码转换成ISO-8859-1码
         */
        public String toISO_8859_1(String str) throws UnsupportedEncodingException {
            return this.changeCharset(str, ISO_8859_1);
        }

        /**
         * 将字符编码转换成UTF-8码
         */
        public String toUTF_8(String str) throws UnsupportedEncodingException {
            return this.changeCharset(str, UTF_8);
        }

        /**
         * 将字符编码转换成UTF-16BE码
         */
        public String toUTF_16BE(String str) throws UnsupportedEncodingException {
            return this.changeCharset(str, UTF_16BE);
        }

        /**
         * 将字符编码转换成UTF-16LE码
         */
        public String toUTF_16LE(String str) throws UnsupportedEncodingException {
            return this.changeCharset(str, UTF_16LE);
        }

        /**
         * 将字符编码转换成UTF-16码
         */
        public String toUTF_16(String str) throws UnsupportedEncodingException {
            return this.changeCharset(str, UTF_16);
        }

        /**
         * 将字符编码转换成GBK码
         */
        public String toGBK(String str) throws UnsupportedEncodingException {
            return this.changeCharset(str, GBK);
        }

        /**
         * 字符串编码转换
         *
         * @param str        待转换编码的字符串
         * @param newCharset 目标编码
         * @return
         * @throws UnsupportedEncodingException
         */
        public static String changeCharset(String str, String newCharset)
                throws UnsupportedEncodingException {
            if (str != null) {
                //用默认字符编码解码字符串。
                byte[] bs = str.getBytes();
                //用新的字符编码生成字符串
                return new String(bs, newCharset);
            }
            return null;
        }

        /**
         * 字符串编码转换
         *
         * @param str        待转换编码的字符串
         * @param oldCharset 原编码
         * @param newCharset 目标编码
         * @return
         * @throws UnsupportedEncodingException
         */
        public static String changeCharset(String str, String oldCharset, String newCharset)
                throws UnsupportedEncodingException {
            if (str != null) {
                //用旧的字符编码解码字符串。解码可能会出现异常。
                byte[] bs = str.getBytes(oldCharset);
                //用新的字符编码生成字符串
                return new String(bs, newCharset);
            }
            return null;
        }

        private static boolean isChinese(char c) {
            Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
            if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
                    || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
                    || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
                    || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_B
                    || ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
                    || ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS
                    || ub == Character.UnicodeBlock.GENERAL_PUNCTUATION) {
                return true;
            }
            return false;
        }

        public static void main(String[] args) throws UnsupportedEncodingException {
            ChangeCharset test = new ChangeCharset();
            String str = "This is a 中文的 String!";
            System.out.println("str: " + str);
            String gbk = test.toGBK(str);
            System.out.println("转换成GBK码: " + gbk);
            System.out.println();
            String ascii = test.toASCII(str);
            System.out.println("转换成US-ASCII码: " + ascii);
            gbk = test.changeCharset(ascii, ChangeCharset.US_ASCII, ChangeCharset.GBK);
            System.out.println("再把ASCII码的字符串转换成GBK码: " + gbk);
            System.out.println();
            String iso88591 = test.toISO_8859_1(str);
            System.out.println("转换成ISO-8859-1码: " + iso88591);
            gbk = test.changeCharset(iso88591, ChangeCharset.ISO_8859_1, ChangeCharset.GBK);
            System.out.println("再把ISO-8859-1码的字符串转换成GBK码: " + gbk);
            System.out.println();
            String utf8 = test.toUTF_8(str);
            System.out.println("转换成UTF-8码: " + utf8);
            gbk = test.changeCharset(utf8, ChangeCharset.UTF_8, ChangeCharset.GBK);
            System.out.println("再把UTF-8码的字符串转换成GBK码: " + gbk);
            System.out.println();
            String utf16be = test.toUTF_16BE(str);
            System.out.println("转换成UTF-16BE码:" + utf16be);
            gbk = test.changeCharset(utf16be, ChangeCharset.UTF_16BE, ChangeCharset.GBK);
            System.out.println("再把UTF-16BE码的字符串转换成GBK码: " + gbk);
            System.out.println();
            String utf16le = test.toUTF_16LE(str);
            System.out.println("转换成UTF-16LE码:" + utf16le);
            gbk = test.changeCharset(utf16le, ChangeCharset.UTF_16LE, ChangeCharset.GBK);
            System.out.println("再把UTF-16LE码的字符串转换成GBK码: " + gbk);
            System.out.println();
            String utf16 = test.toUTF_16(str);
            System.out.println("转换成UTF-16码:" + utf16);
            gbk = test.changeCharset(utf16, ChangeCharset.UTF_16LE, ChangeCharset.GBK);
            System.out.println("再把UTF-16码的字符串转换成GBK码: " + gbk);
            String s = new String("中文".getBytes("UTF-8"), "UTF-8");
            System.out.println(s);
        }
    }
}

